Regex Exclude Specific String

Question

I need to have a .NET regex to match "[@foo]" from "applicant_data/contact_number[@foo]" w/c I can already do using the pattern "\[@(.*?)\]".

However I want to make an exception so that "applicant_data/contact_number[@foo=2]" does not match the pattern. So the question is what should be the regular expression so that it will get any valid alphanumeric ([@bar],[@theVar],[@zoo$6]) but not [@bar=1], [@theVar=3]?

Is the word foo constant or can it vary? Also, you want to exclude it only for the number 2 or any number? — Gurmanjot Singh
– Gurmanjot Singh, Commented Dec 18, 2017 at 9:55

Cylian · Accepted Answer · 2017-12-18 10:07:46Z

1

You may try this:

\[@[\w-]+(?!=)\]

the explanation:

"\[" &       ' Match the character “[” literally
"@" &        ' Match the character “@” literally
"[\w-]" &    ' Match a single character present in the list below
                ' A “word character” (Unicode; any letter or ideograph, digit, connector punctuation)
                ' The literal character “-”
   "+" &        ' Between one and unlimited times, as many times as possible, giving back as needed (greedy)
"(?!" &      ' Assert that it is impossible to match the regex below starting at this position (negative lookahead)
   "=" &        ' Match the character “=” literally
")" &
"\]"         ' Match the character “]” literally

Hope this helps!

answered Dec 18, 2017 at 10:07

Cylian

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2 Comments

james Over a year ago

any chance you could expand the answer as to only get "foo" from "@[foo]" meaning find a word character (without the "=" sign) preceded by "@[" and succeeded by "]".

Cylian Over a year ago

i think i misunderstood your requirement... (?<=@\[)\w+(?=\])...this would match word-characters surrounded by @[ at start and by ] at end...

Gurmanjot Singh · Accepted Answer · 2017-12-18 10:12:04Z

1

Try this regex:

\[@(?![^\]]*?=).*?\]

Click for Demo

Explanation:

\[@ - matches [@ literally
(?![^\]]*?=) - negative lookahead to make sure that = is not present anywhere before the next ]
.*? - matches 0+ occurrences of any character except a newline character
\] - matches ] literally

edited Dec 18, 2017 at 10:12

answered Dec 18, 2017 at 9:59

Gurmanjot Singh

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1 Comment

james Over a year ago

thanks @Gurman "=2" is not constant it could be "=bar". Frankly just detecting the presence of "=" sign inside "[@theWord]" would work.

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